Calculate the De Broglie wavelength of an electron traveling with a velocity of 9.0 * 10³ kilometers per second. The mass of an electron is 9.1 x 10ˉ²⁸ g. )( c= 3 x 10⁸ m/s, h=6.63x10ˉ³⁴ J•s)

You're actually looking for the de Broglie wavelength here, which, ... the product between its mass and its velocity, as shown by the equation ... kg103g =9.1⋅10−31.kgv=7.0⋅103km s−1⋅103.m1km =7.0⋅106. ... electrons to kilograms and the velocity to meters per second because ... 1 J=1 kg m2s−2.

Explanation:

the answer is na (sodium)

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.